1. Field of the Invention:
Charges of static electricity can develop on clothing as the wearers of the clothing move their arms and legs and also as they walk on non-conductive floor surfaces. When the relative humidity of the ambient atmosphere is very low, the charges of static electricity tend to develop readily; and those charges can become sizeable--in many instances reaching several thousands of volts. Static electricity charges are not only annoying--because they cause clothing to cling to the wearer's body, and also because they cause fine particles of lint and dust to collect on the clothing--but those charges can damage sensitive microcircuits, sensitive integrated circuits and other sensitive semi-conductors which are being handled by the wearer of the clothing. Specifically, charges of static electricity which are as small as six hundred volts can damage some sensitive microcircuits, sensitive integrated circuits and other sensitive semi-conductors. To minimize the development of charges of static electricity on clothing, and also to limit the sizes of any such charges which may develop on clothing, efforts have been made to incorporate electrically conductive elements into clothing or to apply antistatic chemicals to the clothing.
2. Description of the Prior Art
Antistatic chemicals are marketed in the form of additives to detergents, in the form of aerosol sprays to be sprayed onto clothing, and in the form of additives to "washes"; and those chemicals are helpful in reducing the tendency of clothing to cling to the wearer. However, those chemicals are not able to keep potentially-damaging charges of static electricity from developing on the surface of clothing. Also, those chemicals are not permanent in nature, and hence must be applied after each washing of the clothing. Further, some of those chemicals can form films on the surfaces of the clothing which can flake off and become contaminants, and hence make the treated clothing unusable in "clean rooms". In addition, those chemicals produce variable results where the persons who use those chemicals fail to use the specified amounts and proportions of those chemicals.
Metallic laminate threads--each of which consisted of a bottom ply of thin narrow plastic, a middle ply of thin narrow metal and top ply of thin narrow plastic--have been used. However, the conductivity of the metal in the middle plies of those metallic laminate threads was so high that those middle plies were made with gaps therein to protect persons--who walked on rugs made with yarns in which those metallic laminate threads were incorporated--from the risk of electrocution. Those metallic laminate threads were rectangular in cross section and were relatively wide--frequently one hundredth of an inch wide; and hence were not usable in making thin, light clothing for "clean rooms". Also, because those middle plies of metal were extremely thin--frequently forty-five hundred-thousandths of an inch thick--and because only the thin edges thereof were exposed, those metallic laminate threads could not keep sizeable charges of static electricity from forming on the surfaces of any garment in which they might be incorporated.
Large numbers of lengths of small diameter stainless steel threads or wire have been incorporated into yarns which have been used to weave fabrics; and those lengths of stainless steel threads or wire have enabled clothing, which was made from those fabrics, to discharge potentially-damaging charges of electricity and also to reduce the tendency of such clothing to cling to the wearer. However, those fabrics are not limited-linting fabrics, and hence they are not desirable for use in "clean rooms".
Monofilaments of polymeric material have had conductive particles embedded in the surfaces thereof to make those monofilaments conductive; and those monofilaments have been incorporated into clothing. In some instances, those monofilaments have been incorporated into warp knit fabrics; and, when properly incorporated into such fabrics, those monofilaments have been able to keep potentially-damaging charges of static electricity from developing on the surface of clothing made from those fabrics. However, those warp knit fabrics could not substantially prevent the passage therethrough of hair and flaked-off particles of skin, and hence were not suitable for use in "clean rooms". Those monofilaments also have been incorporated into woven fabrics and, when so incorporated, those monofilaments have minimized the tendency of clothing, made from those fabrics, to cling to the wearer. However, those monofilaments were unable to keep potentially-damaging charges of static electricity from developing on the surface of clothing made from those fabrics.